amitym t1_jea8msl wrote

Yes, and it will of course be slightly less than that in an orbit just outside the event horizon.

But escape velocity isn't the same as local orbital velocity, right? Escape velocity is the speed you have to start out at if you want to coast the rest of the way and still escape the orbit of your primary. Your orbital velocity in your local frame of reference should be much less than the speed of light in this case.

So you should be able to exit your secret black hole lair through gradual velocity changes, from continuous acceleration or other means. The reason I mention that is that it seems technologically somewhat more feasible than stipulating, "okay well first off, you start by going at the speed of light...."


amitym t1_jea7h3g wrote

It's the gravitational acceleration at that distance from a body of that mass, at least based on the random internet calculator I used. (~500 m/s^(2))

Under that kind of gravity, it doesn't really matter how big you are or what your orientation is. The gradient isn't going to be enough to spaghettify you. It might matter if you want to build a large structure in close orbit around the black hole, but even then, a reasonably sized, properly engineered steel-reinforced structure should be able to handle that level of stress.


amitym t1_je89s60 wrote

It doesn't have to do with inertia. Astronauts orbiting Earth feel like they're falling, instead of feeling like they're being extruded into a thin bloody dribble, because the pull of gravity is effectively the same at their feet as it is at their heads.

That's not the case when very close outside the Schwarzchild radius of smaller black holes. But at 30 billion solar masses, the Schwarzchild radius is so far out from the singularity that the gravitational gradient is, as around Earth, negligible.


amitym t1_je7mice wrote

Yes, practically speaking, but under a steep enough gravitational gradient you can no longer ignore the difference between, for example, the gravity acting on your head versus your feet. Or one end of a structure versus another. That's what causes "spaghettification" for example.

However in this case the gravitational gradient is still pretty shallow, as far as I can tell.


amitym t1_je6yb8t wrote

Based on a random internet Schwarzchild Radius calculator, at 30Bn times Solar mass, that would put the event horizon at an equivalent distance of about 15 times further than Pluto. Anyone in orbit just above the event horizon would move at about 6km / s, roughly comparable to low Earth orbital velocity, and would be subject to only 50 gees -- hard to escape from but not impossible, also not nearly enough to cause "spaghettification," or appreciable time dilation either.

Aside from being fried by the hard radiation pouring out from right under you, sounds quite livable! You'd never have to worry about getting too cold, anyway.


amitym t1_ja7ni9s wrote

First and foremost, stop reading stuff that tells you that you are doomed and there is no hope. That stuff is not there to give you a realistic understanding of the world. It's there to make you paralyzed and perpetually clicking on things while exerting no actual effort toward any kind of positive change in the real world.

I'm not exaggerating. Doom-bait is engineered by marketing firms and algorithms to give you all the thoughts you just wrote out, and to do nothing about any of it. That's not a metaphor or hyperbole. They literally sit around and figure out how to achieve this effect, because it makes you more profitable to them.

There is even a term for this in the social media biz, although I forget what it's called. Induced amotivation or something?

So first things first, if you're drinking poison, first thing you do is stop drinking the poison. You don't need to answer the question, "well but how is this poison going to get drunk if I don't drink it?" or "how will I find other poison to drink if I stop drinking this poison?"

You are allowed to just stop!

Next, you are already interested in energy and climate change, there is a huge amount of work to do there. And there is a huge amount of work already going on. Who near you is working on renewable energy? Maybe you can volunteer to help them with what they do. Whether it is political organizing or literally setting up solar panels, anything you learn and any experience you gain will be helpful. Maybe there are other defossilization efforts you can be a part of. You do not need to build by yourself a huge space mirror 1000km wide that saves humanity or whatever. You will at least need a university degree first, in order to do that!

For now you can start smaller.

Big changes are possible. They happen. The thing is, they usually involve the work of many thousands and hundreds of thousands of regular people all acting toward a common goal. Eventually you get treaties and people in expensive suits signing things and shaking hands and so on but those moments are built on top of the foundation laid by regular people each doing small work over time.

So you can start by being one of those people, in your own small way. It all counts.

(And don't forget to stop drinking the poison.)


amitym t1_ja5g0lg wrote

Well like when it becomes tree-stuff it is often split up, the tree will retain some water as part of its inventory of healthy-tree biomass but also some of the H and some of the O in the H₂O gets turned into sugar and starch and structural carbohydrates and proteins and stuff.

You can regard those other substances as a reservoir for water, in a sense, because over time as they are metabolized or whatever happens to them they may break back down into water again. As part of the tree's life cycle.

But in terms of where it ultimately goes? Sure absolutely, someday the tree will die, and when it dies the tree will decompose, and some part of the tree's biomass will be eaten by bacteria, fungi, and the other usual suspects. During that process much of the tree will be turned back into water again. And then go be part of the soil, from which new sprouts will sprout again, and so on and so forth.

Some statistically minded biologist might be able to give an estimate of how long your average water molecule remains water continuously over a timeframe like that (let's say several hundred years). It might be that a lot of the water a tree consumes just always remains water. Or it might be that most of it changes form! That is an interesting question.


amitym t1_j9zlnf6 wrote

Whatever water the plant doesn't cycle back into the atmosphere gets turned into more plant.

Like... look at a tiny little tree sprout. Now look at a huge tree, hundreds of years old. Huge difference in size, right? Where does all that tree come from?

It's the water that didn't get cycled back. Turned into tree. (Also some other things aside from water, that also got turned into tree.)


amitym t1_j9ro0xf wrote

>Wonder what qualifies as low income in Cali though.

It doesn't really matter. The Bay Area needs housing units en masse. After 300,000 new units have been built, we can assess whether there needs to be more targeted construction, but up until now a hyperfocus on whether the 20 new units of X project will be "low-income enough" has missed the point that 20 new units doesn't mean diddly squat, at any income level. It's the massive crushing scarcity of the entire market that's squeezing everyone.

Gatekeeping NIMBY crusaders have until now successfully derailed the conversation into the ditch of nitpicking over insignificant disputes. The real goal was to avoid large-scale changes in the housing market entirely. Fortunately it seems they have finally been thrown back.


amitym t1_j83wj5k wrote

Yeah right on.

To understand why it's no problem as this commenter said, remember that the thrust itself is comparable to forces easily within the usual realm of civil engineering tasks.

We don't use rockets to get to space because they generate cosmically far-fetched amounts of thrust, but rather because they can generate thrust reliably and continuously over an extended period, largely indifferently to the environment around them.

It's a similar principle as how a jet liner with engines capable of transporting hundreds of people at Mach 0.9 can be held in place by a couple of wooden chocks.


amitym t1_j709r1s wrote

Interestingly, the hypothetical ocean would be deeper under the ice than that, implying a much lower background radiation exposure than on Earth.

Which suggests a lower mutation rate for any life forms that live there. Although of course that might depend on whether they evolved to be more mutation prone as a meta-evolutionary strategy....